Is Thomas Beatie the first legal pregnant man? That's a question that can't be answered with absolute certainty.
Stephanie Brill, director of Maia Midwifery & Preconception Services and founder of Gender Spectrum, told ABC's Barbara Walters that Beatie was "by no means" the first pregnant man.
"He is the first man to go public with his pregnancy on such a widespread level," Brill said.
But how does one define who is a pregnant man? For one thing, there is a bewildering array of requirements for legally changing sex and these vary from state to state, making it difficult to say who is legally male and who isn't.
Also, the few transgender men who have become pregnant do not make their pregnancies public, so it's unclear how many have gotten pregnant before Beatie, and whether they were legally male at the time of their pregnancy.
The Village Voice reported on one pregnant man several years ago. Matt Rice, a female-to-male transsexual, conceived using artificial insemination and gave birth to a baby boy in 1999.
And then there is the case of Daniel Burghammer. Christened and raised as male, Burghammer became a blacksmith, husband and Italian soldier more than 400 years ago. But in 1601, he scandalized his regiment when he gave birth to a baby girl.
According to biologist Anne Fausto-Sterling, who discussed this story in her book, "Sexing the Body," Burghammer was a hermaphrodite, meaning he had both male and female reproductive organs. That made his pregnancy, and even breastfeeding, possible.
Brill, who is also a midwife and founder of the educational group Gender Spectrum, first delivered the baby of a transgender man more than eight years ago. She now knows of as many as 40 men who have gotten pregnant. In the coming years, Brill expects that number to rise significantly.
"Most transgender men will choose another path to parenthood, but some will choose this path," Brill said.
According to Brill, Beatie's case is significant because of what it says about dramatic societal shifts now under way.
"I think that what it's helping us to do is understand that the face of family is changing," Brill said. "It's been changing for a long time.
"Each time that something pushes the edge of that family, our society at first tends to think it's wrong," Brill added, "whether that was people having interracial babies, or whether that was single mothers by choice, [or] whether that was gay or lesbian families. The same is true for transgender families."
No longer living on the fringes of society, transgender families are quietly raising their children in towns and neighborhoods across the country.
Take the case of Andey and Leaf Nunes, and their son Antonio. Even in San Francisco, where the two men live, their relationship raises eyebrows and the questions of, "What is a woman? What is a man?"
"We're a gay male couple that got to have a child the old-fashioned way," said Andey, a transgender man. "I am Antonio's biological mother on his birth certificate."
How is that possible? Leaf is biologically male, while Andey was born female.
When the two of them married, Andey was still Angie. But by then, she was already struggling with the feeling that she was really a man. Angie delayed her transition in order to get pregnant.